1. Field of the Invention
The disclosure generally relates to an apparatus for power management, and more particularly, relates to an apparatus for power management that can switch between an APT (Average Power Tracking) mode and an ET (Envelope Tracking) mode for use in a mobile device.
2. Description of the Related Art
In a traditional mobile device, a DC to DC (Direct Current to Direct Current) converter can control a power amplifier (PA) to operate in two power-saving modes. One is an APT (Average Power Tracking) mode, and the other is an ET (Envelope Tracking) mode. A system is designed to select only one of them, and cannot switch between them. In the APT mode, the mobile device discretely adjusts a supply voltage of the power amplifier. In the ET mode, the mobile device adjusts the supply voltage of the power amplifier according to a feedback RF (Radio Frequency) signal.